The Sirius binary star system consists of a main sequence primary star of spectral class A1 (Sirius A) and a white dwarf companion (Sirius B) in orbit around their common center of mass with a period of about 50 years. The system is approximately 8.6 light years from Earth and lies in the constellation Canis Major (the Big Dog). The primary star is the brightest star in our sky other than the Sun.